Arcing in a plasma reactor during processing of a semiconductor workpiece or wafer can destroy the workpiece or make unusable, or contaminate the reactor chamber. Therefore, detection of arcing to stop a plasma reactor from processing further wafers is essential to avoid damage to a succession of wafers. In physical vapor deposition (PVD) plasma reactors, arc detection has been confined to arcing at the sputter target at the reactor ceiling. Such arc detection has been made by monitoring the output of the high voltage D.C. power supply coupled to the sputter target at the ceiling. Voltage or current transients can reflect arcing events. While this approach has provided reliable indication of arcing events occurring at or near the sputter target at the reactor ceiling, it has not provided a reliable indication of arcing at the wafer (wafer level arcing). Detection of wafer level arcing can be particularly difficult because of RF noise surrounding the wafer caused by RF power applied to the wafer support pedestal and, in some reactors, to RF power applied to an inductive coil on the chamber side wall. Another challenge is the large dynamic range of transients or noise caused by RF generator transitions called for by a process recipe, for example. Such transition-induced transients must be distinguished from transients caused by arcing at the wafer level.
Plasma reactors typically have components within the reactor chamber that are consumed or degraded by their interaction with plasma. In a PVD reactor, the consumables may include the sputter target at the ceiling, an internal side wall coil and a process ring kit surrounding the wafer support pedestal including the electrostatic chuck (ESC). As such consumables degrade or are physically changed, they become more susceptible to arcing. The problem is how to determine when each consumable should be replaced before there is an arc.